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  <topic id="topic_fstrm">
    <title>btree_gin</title>
    <body>
      <p>The <codeph>btree_gin</codeph> module provides sample generalized inverted index
        (GIN) operator classes that implement B-tree equivalent behavior for certain data
        types.</p>
      <p>The Greenplum Database <codeph>btree_gin</codeph> module is equivalent
        to the PostgreSQL <codeph>btree_gin</codeph> module. There are no
        Greenplum Database or MPP-specific considerations for the module.</p>
    </body>
    <topic id="topic_reg">
      <title>Installing and Registering the Module</title>
      <body>
        <p>The <codeph>btree_gin</codeph> module is installed when you install
          Greenplum Database. Before you can use any of the functions defined in the
          module, you must register the <codeph>btree_gin</codeph> extension in
          each database in which you want to use the functions:</p>
      <codeblock>CREATE EXTENSION btree_gin;</codeblock>
        <p>Refer to <xref href="../../install_guide/install_modules.html"
            format="html" scope="external">Installing Additional Supplied Modules</xref>
          for more information.</p>
      </body>
    </topic>
    <topic id="topic_issues">
      <title>Greenplum Database Limitations</title>
      <body>
        <p>The Pivotal Query Optimizer (GPORCA) does not support queries that access an
          index with <codeph>op_class</codeph>, such queries will fall back to the
          Postgres Planner</p>
      </body>
    </topic>
    <topic id="topic_info">
      <title>Module Documentation</title>
      <body>
        <p>See <xref href="https://www.postgresql.org/docs/9.4/btree-gin.html"
          format="html" scope="external">btree_gin</xref> in the PostgreSQL
          documentation for detailed information about the individual functions in
          this module.</p>
      </body>
    </topic>
  </topic>
</dita>
